A known folding blade knife comprises a blade member and two U-shaped guard members, the free ends of both U-shaped guard members being pivoted to the rear end of the blade member on mutually perpendicular non-intersecting axes, such that in storage the point of the blade is enclosed in the folds of the two guard members, one guard member covering the blade edges of the blade member and the other guard member covering the faces of the blade member. In this known folding blade knife, the first guard member to be unfolded from the blade member is the guard member covering the blade edges of the blade member, the second guard member to be unfolded from the blade member being the guard member covering the faces of the blade member. The user of the known knife is liable to cut himself on the sharp edge of the blade member when unfolding the second guard member. Furthermore, this known knife has no spring detent action to hold the guard members in position relative to the blade member, either when the blade member is in storage or when it is extended for use. Furthermore, the blade member is in one piece and cannot be replaced.